The present invention is directed primarily to devices for generating an axial oscillating movement for use with oscillating rollers of an inking unit or a dampening unit of a printing press. Such rollers are generally rotated through frictional contact with an adjacent roller or with an adjacent cylinder, which is, in turn, driven either directly or indirectly through the machine drive for the associated printing press.
A device for the axial reciprocating movement of an oscillating roller is known from DE 196 03 765 A1. An external power source, particularly in the form of a piston/cylinder unit, is provided for the accomplishment of the reciprocating movement. According to one preferred embodiment of that prior device, the oscillating roller can be equipped, in its interior, with two pressure chambers. A differential pressurization of these two pressure chambers causes the reciprocating movement of the oscillating roller. In this device, compressed air is provided as the working medium, which compressed air is generated by an external compressor.
Another device, for use in generating axial movements of the oscillating rollers of inking and dampening units of printing presses, is known from the disclosure of DE-OS 2 235 313. In this prior device, an external, dual-action cylinder is provided, whose piston forms one arm of the oscillating roller. Hydraulic oil, which is used as the working fluid, is supplied alternatingly to the pressure chambers of the cylinder through an external hydraulic drive and an external switchover valve. The hydraulic oil is stored in an external oil reservoir.
A self-oscillating roller assembly is known from U.S. Pat. No. 5,329,851 A. A working fluid is supplied alternatingly to pressure chambers, which act in opposite directions. The working fluid is provided from an external compressed air source through a timer-controlled, external switchover valve.
In contrast to the motor-actuated roller drives, which are described above, it is also known to provide a purely mechanical, self-actuating drive for imparting axial oscillating movement. In this connection, see, for example, DE 29 31 141 C3. The device which is disclosed in DE 29 31 141 C3 is actuated via the rotational movement of the roller shell. The oscillating movement of the roller is being generated through a ball and a bushing. The bushing is seated so as to be non-rotatable and has a groove which is skewed or angled. Between that groove and a second groove, which extends perpendicular to the center axis of the oscillating roller, the ball rolls in a bushing which is stationarily positioned in the roller shell. With rollers of this type having mechanical friction drives, there is a danger of the rollers becoming locked, which roller locking can lead to serious consequential damage. Moreover, it is not possible to vary the oscillation frequency, which frequency is permanently established by the structural conditions that exist in the particular roller.
DE 36 20 423 A1 describes various embodiments of drives for use in imparting axial movement to oscillating rollers. In one embodiment of this prior device, the roller is moved by the use of a pneumatic system. The pneumatic medium supply is located outside of the roller. In another embodiment of this prior device, axial movement is generated through the use of a mechanical transmission.
DE 10 2005 019 266 A1 discloses a drive for an inking roller of a printing press. The drive comprises a hydraulically actuable lift cylinder, which displaces the roller in an axial direction in an oscillating fashion. The requisite pneumatic medium for the hydraulically actuable lift cylinder is supplied via a pump.